This invention relates generally to a mounting structure for electric motors utilized to drive vehicle axles, and specifically to a mounting structure for a frame mounted electric motor.
Typically, mass transit vehicles such as buses and trolleys provide a floor substantially lower than common in other vehicles to aid loading and unloading of passengers. The low floor is made possible by an inverted axle assembly that transmits power to the driven wheels along an axis other than the axis of wheel rotation. Conventional inverted axle assemblies are bulky and complex. One known alternative to an inverted drive axle is the use of a single electric motor at each drive wheel. The electrical motor at each drive wheel does not require an axle assembly extending laterally across the vehicle and therefore allows the lower floor.
Typically, electric motors are mounted such that the driven shaft of the electric motor is concentric with the axis of rotation of the driven wheel. Such a configuration requires that the electric motor become part of the mass suspended from vehicle frame. Electric motors are of considerable weight and this weight is added to the suspended mass that also includes the driven wheel and any suspension members. The additional weight requires that the suspension members be of a larger capacity in order to accommodate the added weight of the electric motor.
An improvement on suspending the motor parallel with the driven wheel includes mounting of the electric motor transversely relative to the driven axle. The transverse mounting of the motor provides for additional space in the motor vehicle to allow for the lower floor to be extended outward towards the outboard portion of the motor vehicle. However, in this configuration the motor is still part of the suspended mass along with the wheel and the other suspension components.
Accordingly, it is desirable to design an electric motor mounting assembly for driving vehicle wheels that does not require the electric motor to be suspended from the frame of the vehicle.